An improvised mortar system used by the Provisional Irish Republican Army (PIRA), an Irish guerilla group, against the British army and Police in the six British-controlled counties in the north of Ireland. So-called due to the major damage they caused against army and police barracks.

A three-litre bottle of cider. Most commonly used in Belfast, Ireland.

In Ireland, the old British police and army stations are often called barracks, and the idea was that the Irish used to fill massive bottles up with petrol, light them, and throw them at these British barracks, effectively "busting" the barracks.

So now, a 3l bottle of cidre, due to its size and volume, is now provisionally known as a 'barrack-buster.'